1. Field of Invention
The present invention relates generally to output buffer circuits.
2. Related Art
An output buffer that operates in a parallel interface, such as the Peripheral Component Interface (PCI)-X (where X indicates enhancement to PCI), is required to operate at ever increasing data rates. Typically, the output buffer is also required to drive large capacitive loads. To help meet such requirements, the output buffer needs to have an output slew rate and an output impedance that are both well controlled.
With the reduced power supply voltages used on deep sub-micron CMOS Integrated Circuit (IC) chips, in addition to the increased operating speeds mentioned above, the impact of noise generated by simultaneous switched outputs of a conventional output buffer can cause spurious components that interfere with other signals on a given IC chip or on an application circuit board/card using the conventional output buffer. Thus, there is a need for an output buffer that reduces or even eliminates such interference.